Liquid metering device having an automatically variable discharge

ABSTRACT

In a liquid metering device of the type having piston-cylinder assembly connected for receiving pressurized liquid and discharging slugs of the liquid alternately from opposite ends of the cylinder of the piston-cylinder assembly upon reciprocative movement of the piston therein, the improvement comprising a regulating means for automatically controlling the length of travel or stroke of the piston in response to the change in angular velocity of a rotating mechanism. The regulating means includes a valve actuatable by an inertia means which senses the r.p.m. of the rotating mechanism.

United States Patent Corwin 1 Feb. 1, 1972 I54] LIQUID METERING DEVICEHAVING AN AUTOMATICALLY VARIABLE DISCHARGE [72] Inventor: Howard RussellCorwin, North Caldwell.

[73] Assignee: Curtiss-Wright Corporation {22] Filed: Mar. 2, I970 [2]]Appl. No: 15,393

2,9IO,976 I 1/1959 Fancher ..4l7/294 2,538,982 l/19Sl Roosa ..4l7/2l4FOREIGN PATENTS OR APPLICATIONS 729.483 5/1955 Great Britain ..4l7/349Primary Examiner-William L. Freeh Attorney-Arthur Frederick and VictorD. Behn [57] ABSTRACT In a liquid metering device of the type havingpiston-cylinder assembly connected for receiving pressurized liquid anddischarging slugs of the liquid alternately from opposite ends of thecylinder of the piston-cylinder assembly upon reciprocative movement ofthe piston therein, the improvement comprising a regulating means forautomatically controlling the length of travel or stroke of the pistonin response to the change in angular velocity ofa rotating mechanism Theregulating means includes a valve actuatable by an inertia means whichsenses the rpm. of the rotating mechanism.

4 Claims, 8 Drawing Figures PATENTED FEB 1 I972 SHEET 1 0F 2 ATTORNEYPATENTED FEB 1 I972 SHEET 2 OF 2 ATTORNEY LIQUID METERING DEVICE HAVINGAN AUTOMATICALLY VARIABLE DISCHARGE The invention relates to liquidmetering devices and, more particularly, to liquid metering deviceswhich are capable of varying the amount of liquid discharge inaccordance with r.p.m. of another device.

BACKGROUND OF THE INVENTION In liquid metering devices, such as thelubricant metering mechanism disclosed in the U.S. Pat. to Kemp, No.3,172,578, the amount of lubricant metered cannot be automaticallyvaried. While such metering devices can be mechanically modified toachieve a difi'erent rate of discharge, the variable output is notautomatically adjustable in relation to the r.p.m. of the apparatus tobe lubricated. A liquid metering device which is capable of providinglubricant emissions in varying amounts is especially desirable in rotarypiston, combustion engines where the apex seals of the engine rotorrequire specifically directed lubrication. The problem in suchapplications is that more lubricant is required at the apex seals athigh r.p.m. of the engine rotor than at low r.p.m. Thus, to insureadequate lubrication at high engine r.p.m. the metering device isconstructed and arranged to deliver the quantity of lubricant requiredfor proper lubrication at high engine r.p.m. and, therefore, producesexcessive lubrication of the apex seals at low engine r.p.m. Obviously,this results in excessive consumption of oil and, in the engine exhaust,a higher level of undesirable hydrocarbon emissions.

Accordingly, it is an object of the present invention to provide aliquid metering device in which the liquid discharge rate automaticallyvaries in proportion to the r.p.m. of a rotating mechanism.

It is another object of this invention to provide a liquid meteringdevice which is combined with a pump into a single, compact. unitarystructure.

A feature of this invention is the control piston means for changing thelength of the stroke of the shuttle piston to thereby change thequantity of liquid discharged by each reciprocative movement of theshuttle piston.

Another feature of the present invention is the inertia means whichautomatically senses r.p.m. and coacts with a dump valve to actuate thelatter and thereby control the position of a control piston means.

SUMMARY OF THE INVENTION It is, therefore, contemplated by the presentinvention to provide a novel liquid metering device which comprises ahousing in which a metering cylinder is supported rotation about itslongitudinal axis. A free floating, double-acting piston is disposed forreciprocation in the metering cylinder. The housing is provided with aliquid inlet means communicating with a source of pressurized liquid toreceive such liquid and a liquid outlet means communicating with a placeof use of the liquid to pass the liquid to the latter. The cylinder hasport means disposed to communicate alternately the opposite ends of thepiston with the inlet means and the outlet means to thereby effectreciprocation of the piston and the intermittent discharge of liquidthrough the outlet means. A regulating means is provided to control thelength of travel of the piston in response to the change in r.p.m. of arotating mechanism. The regulating means includes a plunger-cylindermeans which is slidably disposed in said housing for movement relativeto the cylinder and the piston. A control passage means is provided inthe housing to communicate the inlet means with the plunger-cylindermeans to convey pressurized liquid to the latter from the inlet meansand thereby urge the plunger-cylinder toward said piston to minimize thelength of the stroke of the piston. The resulting means also includes adumping passageway, the flow through which is controlled by a dumpingvalve. The dumping passageway is disposed in the housing to communicatethe control passage means with a chamber of lower liquid pressure thanthe pressure of the liquid at the inlet means. Also comprising part ofthe regulating means is a valve actuating means constructed and arrangedto sense the r.p.m. of a rotating member and coacting with said dumpingvalve to cause the latter, at a predetermined r.p.m., to be actuated tocommunicate the dumping passageway with the control passage means andcause the plunger-cylinder means to move to increase the length of thestroke of the piston so that increased liquid is delivered to the outletmeans.

In another aspect of this invention, the housing of the liquid meteringdevice also encloses a liquid pump. In this embodiment, the regulatingmeans includes a centrifugal mass means connected to be rotated by theimpeller shaft of the pump to thereby sense the r.p.m. of the shaft.Additionally, in this embodiment, the cylinder may be rotativelyconnected to the impeller shaft to be rotated by the latter.

DESCRIPTION OF THE DRAWINGS The invention will be more fully understoodfrom the following description thereof when considered in connectionwith the accompanying drawings, in which:

FIG. 1 is an end view in elevation of the liquid metering device andpump assembly according to this invention;

FIG. 2 is a longitudinal cross-sectional view taken substantially alongline 2-2 of FIG. I showing the pump assembly;

FIG. 3 is a fragmentary cross-sectional view taken along line 33 of FIG.1, showing the r.p.m. sensing unit of this invention;

FIG. 4 is a view in cross section taken along line 4-4 of FIG. I,showing control piston of the metering device;

FIG. 5 is a sectional view taken substantially along line 55 of FIG. 4;

FIG. 6 is a view in cross section taken substantially along line 6-6 ofFIG. 5;

FIG. 7 is a cross-sectional schematic view, in perspective showing theliquid passageways interconnecting the control piston and dump valveaccording to this invention; and

FIG. 8 is a perspective view of the bellcrank lever of the valveactuating means according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now referring to the drawingand, more particularly, to FIGS. I, 2 and 3, the reference numeral 10generally designates a liquid metering device combined with a liquidpump assembly II in a unitary housing I2. While liquid metering device10 is shown combined with a pump assembly II to constitute analternative embodiment of the present invention, it should be understoodthat the liquid metering device constitutes another embodiment separateand apart from pump assembly 1 I. As will be obvious hereinafter,rotative power for metering device 10 may be obtained from any suitablesource. Likewise, the source of pressurized fluid may be from anysuitable source other than pump assembly II. In addition, while theliquid metering device 10 and pump assembly I I will be described asapplied to the metering and pumping of liquid lubricant, it is to beunderstood that the invention is not limited to such application, butmay be employed to meter any pressurized liquid.

LIQUID PUMP ASSEMBLY The liquid pump assembly II, as shown in FIGS. 1and 2, comprises an impeller shaft I3 journaled in housing 12. The shaftI3 is connected to any suitable source of rotary power (not shown), suchas the rotor shaft (not shown) of a rotary piston engine (not shown),through a gear I4 or other suitable drive means. Suitably connected toshaft 13 for conjoined rotation therewith, are two gear impellers, I5and I6. The gear impeller 15 is constructed and arranged to rotatewithin a gearlike stator 17 and define with the stator a plurality ofsuccessively expanding the contracting working or pumping chambers (notshown) to pressurize liquid lubricant. Similarly, gear impeller I6 isconstructed and arranged to rotate within a gearlike stator I8 andthereby define with the stator 18 a plurality of successively expandingand contracting working or pumping chambers (not shown) to pressurizeliquid lubricant. The gear impeller 15 and its associated stator l7 formpart of a pressure pump while gear impeller 16 and its associated stator18 form part of a scavenging pump. The pressure pump is provided withsuitable inlet and outlet connectiuns (not shown) which communicate withthe working chambers thereof to receive lubricant from a reservoir ofliquid lubricant and force the lubricant to points of lubrication in theengine. The scavenging pump is also provided with suitable inlet andoutlet connections (not shown) in communication with the workingchambers thereof to draw liquid lubricant from a sump (not shown) of anengine and deliver the same to the lubricant reservoir (not shown). Thepressure pump may also be provided with connections (not shown) tosupply pressurized liquid to metering device I as will be more fullyexplained hereinafter.

LIQUID METERING DEVICE As best shown in FIG. 4 and 6, metering device I0comprises a double-acting piston-cylinder assembly consisting of ametering cylinder 19 journaled for rotation within a bore 20 formed inhousing 12 with its longitudinal axis extending substantially normal tothe longitudinal axis of pump impeller shaft 13. A double-acting pistonor shuttle piston 21 is disposed for limited rcciprocative movementwithin longitu dinal bore 22 in cylinder 19. The bore 22 is closed atopposite ends, one end being closed by a plunger 23 of a plungercylinder means 23A, hereinafter more fully disclosed. The cylinder 19 isprovided with two longitudinally spaced ports 24 and 25 whichcommunicate at one end with the pockets defined in bore 22 and theadjacent opposite ends of shuttle piston 2|. The ports 24 and 25 arealso circumferentially offset l80 from each other. A pressurized liquidpassageway 26 is formed in housing 12 to extend in spaced, substantiallyparallel relationship with metering cylinder 19. A tapped bore 27 isprovided to receive a conduit (not shown) which communicates with asuitable source of pressurized liquid, such as the outlet connection(not shown) of the pressure pump of liquid pump assembly ll. Spacedparallel secondary passageways 28 and 29 are formed in housing 12 tocommunicate with passageway 26 and to alternately register with ports 24and 25 as metering cylinder 19 rotates. Two spaced parallel tappedoutlet bores, 30 and 31 are also provided in housing I2 to alternatelyregister with ports 24 and 25 as metering cylinder 19 rotates to receiveliquid lubricant discharged from the ports. Suitable conduits (notshown) are attached at outlet bores 30 and 31 to receive and conduct theregulated amount of lubricant to a place of use, such as the apex sealsofa rotary piston engine.

As best shown in FIGS. 2, 3 and 4, metering cylinder [9 is rotated by aworm 32 which is attached to impeller shaft 13 and a worm wheel 33 whichis secured to the metering cylinder in meshing relationship with worm32. The worm 32 and worm wheel 33 are sized to provide for reduction inangu- [at speed from shaft I3 to cylinder [9. While a speed reductiongearing is shown and described, in other applications of the invention,the cylinder gear drive may provide for no change in r.p.m. or providean increased r.p.m. over the empellcr shaft r.p.m. instead of areduction of shaft r.p.m., without thereby departing from the scope andspirit of this invention. The worm 32 and worm wheel 33 cylinder driveis disposed in a chamber 34 in housing I], which chamber is defined by acavity formed in housing 12 and an overlying end wall 12A of thehousing.

In operation of liquid metering device as thus far described,pressurized oil is conducted to passageway 26, via tapped bore 27 and aconduit (not shown) which carries oil from the pressure pump.Simultaneously, metering cylinder 19 is rotated in bore by pump empellershaft l3, through worm 32 and worm wheel 33, the r.p.m. of meteringcylinder 19 being proportional to the r.p.m. of the empeller shaft. The

pressurized oil flows from passageway 26 into secondary passageways 28and 29. When port 25 comes into register with passageway 29, as shown inFIG. 4, oil flows into port 25 and the pockets in bore 22 adjacent tothe right-hand end (as viewed in FIGS. 4 and 6 of the drawings) ofshuttle piston 21. This pressurized oil forces the shuttle piston to theleft (as viewed in FIGS. 4 and 6) to thereby force from the pocket inbore 22 associated with port 24 a portion of the oil trapped therein.The amount of oil discharged into tapped outlet bore 30 is proportionateto the length of the stroke of shuttle piston 21. Conversely, whenmetering cylinder rotates to bring ports 24 and 25 into register withthe secondary passageway 28 and tapped outlet bore 31, respectively,pressurized oil enters the pocket in bore 22 associated with port 24(adjacent the lefthand end of shuttle piston 21 as viewed in FIGS. 4 and6) to drive the shuttle piston to the right as viewed in FIGS. 4 and 6.As before, the reciprocative movement of shuttle piston 21, forces oiltrapped in the pocket in bore 22 associated with port 25 out of thepocket, through port 25, into tapped outlet bore 317 As previouslystated, the amount of oil displaced is proportionate to the length oftravel or stroke of shuttle piston 21. From tapped outlet bore 31, thedischarged oil forces a like amount of oil to the point of use (notshown), such as the apex seals of a rotary piston engine. To provide forautomatically changing the amount of oil discharged by metering cylinder19 per unit time in relation to the r.p.m. of a rotating mechanism, suchas liquid pump assembly 11, a regulating assembly 35 is provided inmetering device 10.

REGULATING ASSEMBLY The regulating assembly comprises three basicsubasscmblies; which are as follows: the plunger-piston means 23A, adumping valve 36 and a valve actuating means 37. The three subassembliescoact to vary the length of travel or stroke of shuttle piston 21 inresponse to a predetermined r.p.m. of a rotating member.

PLUNGER-PISTON MEANS The plunger-piston means 23A includes. in additionto plunger 23, a piston 38 which is slidably disposed in a recess 39formed in housing wall 12A coextensive with metering cylinder 19. Thepiston 38 defines with the bottom of recess 39 a working chamber 40 forreceiving pressurized liquid, such as oil. The plunger 23 has a bodyportion 41 and an in tegral, reduced diameter shank portion 42 which isslidably receivable in bore 22 of metering cylinder 19. A coil spring 43is disposed around head portion 41 to bear, at one end, against meteringcylinder I9 and, at the opposite end, engage the enlarged head 44 ofplunger 23 to thereby bias the plunger to the right as viewed in FIGS. 4and 6. In this spring biased extreme position, plunger 23 allows shuttlepiston 21 to attain maximum travel, and thus maximum discharge of oil.To adjustably limit the maximum movement of plunger 23 under the urgingof spring 43, a stop 45 is supported in a threaded stud 46 which isturned in a threaded bore 47 as wall 12A. The desired position ofadjustment of stop 45 is fixed by a locknut 48.

DUMPING VALVE As best shown schematically in FIG. 7, pressurized oil isconducted to working chamber 40 by a conduit means comprising twointersecting bores 49 and 50 in wall 12A which bores communicate,passageway 26 with working chamber 40. Control of flow of oil throughbores 49 and 50 is achieved by dump valve 36. The dump valve 36comprises a bore 51 in which a spool-type valve body 52 is disposed forreciprocative movement. The valve body has two spaced land portions 53to define a groove portion 54 therebetween. The bore 5! extends tointersect bore 49 so that when the spool valve body is in the extremeposition, as shown in FIGS. 5, 6 and 7, groove portion 54 allows flowthrough bore 49. Spool valve body 52 is biased in bore 51 to the left,as viewed in FIG. 6, by a spring 55. The

tension of spring 55 is adjustable by means of an adjusting screw 56which is turned in a threaded end portion of bore 5!. A locknut S7 isturned upon screw 56 to secure the screw in the desired position ofadjustment (see FIG. 6). As shown, one of the land portions 53 of spoolvalve body 52, upon actuation of the latter, functions to simultaneouslyinterrupt communication of passageway 26 with working chamber 40 whileopen ing a dump passageway 58 which extends from bore 50 to bore 51. Toprovide for free movement of the spool valve in bore 51 to the right, asviewed in FIG. 6, a vent passageway SIA is provided to prevent liquidentrapment ahead of spool valve body 52 in bore 51. The vent passagewaySIA extends from bore 51, through wall 12A, to communicate with cavity34. To actuate spool valve body 52 against the force of spring 55, spoolvalve body 52 has a coaxial extension 59 which projects into cavity 34and into contact with valve actuating means 37 VALVE ACTUATING MEANS Thevalve actuating means 37 comprises, as best shown in FIGS. 2, 3 and 6,an inertia mass means of flyweight ball assembly 60 coacting with abellcrank mechanism 61.

The flyweight ball assembly 60 comprises a cup-shaped disk 62 mounted ona reduced diameter portion 63 of shaft 13 extending into cavity 34. Thedisk 62 is secured by a pin 64 to shaft extension 63 so that disk 62rotates with shaft [3. The disk 62 has a plurality of circumferentiallyspaced, radially ex tending, inclined grooves 65 (only two of which areshown in FIG. 2). A ball 66 is disposed in each of the inclined grooves65, which balls are retained in their associated grooves by a retainingplate 67. The retaining plate is supported on shaft extension 63 forlimited slidable, axial movement under the urging of balls 66 as thesame ride outwardly in grooves 65. The retaining plate 67 is biasedagainst balls 66 by spring 55 through spool valve body 52 and abellcrank lever 68. As best shown in FIGS. 6 and 8, bellcrank lever 68consists of an L"- shaped body member having a bifurcated portionforming a pair of legs 69 and a single leg portion 70 extendingsubstantially normal to the plane of the legs 69. A portion of the bodymember adjacent opposite sides of leg portion 70 is rolled to form apair of hinges 71. The bellcrank lever 68 is pivotally supported on wall12A by a pivot pin 72 which extends through spaced ears 73 and 74projecting from wall 12A and hinges 71 of the lever. The bellcrank lever68 is positioned so that the distal end portions of legs 69 contactretaining plate 67 and leg 70 engages the distal end of extension 59 ofspool valve body 52.

OPERATION As can now be readily seen, as the angular velocity r.p.m. ofshaft I3 increases and reaches a predetermined velocity, as determinedby the adjustment of spring 55, balls 66 are urged by the centrifugalforce acting thereon to ride outwardly in inclined grooves 65. As balls66 move outwardly in grooves 65, retaining plate 67 is moved along thelongitudinal axis of shaft extension 63 to the left as viewed in FIG. 2and to the right as seen in FIG. 3. The movement of retaining plate 67pivotally moves bellcrank lever 68, which movement, in turn, forcesspool valve body 52 against the tension of spring 55. As can best beseen in FIG. 6, this axial movement of spool valve body 52 in bore 51unseals dump passageway 58 and simultaneously closes off bore 49 therebypreventing pressurized liquid from passageway 26 reaching chamber 40and, at the same time, bleeding off pressurized oil from working chamber40 to cavity 34, via bore 50. Any liquid in bore 51, trapped betweenspool valve body 52 and screw 56, is released, through vent passagewaySIA, so that the liquid does not interfere with the movement of spoolvalve body 52. The reduction of fluid pressure in chamber 40, permitsspring 43 (see FIG, 4) to move plunger 23 to the right as viewed inFIGS. 2 and 6. This movement of plunger 23 allows, as previouslydescribed, a greater stroke or travel of piston 21, and thus increasedamounts of oil to be discharged through tapped outlets 30 and 31.

When the angular velocity (r.p.m.) of shaft 13 decreases, below thepredetermined r.p.m. balls 66 move radially inwardly in inclined grooves65 as the centrifugal force acting thereon diminishes. The inwardmovement of balls 66, allows plate 67 to move axially along shaftextension 63 under the urging of the force of spring 55, which force istransmitted from the spring, through spool valve body 52, its extension59, and bellcrank lever 68, to plate 67. Movement of spool valve body 52to the left, as viewed in FIG. 6, closes dump passageway 58, whilesimultaneously restoring communication between bores 49 and 50 andchamber 40. With communication restored between chamber 40 andpassageway 26 and the closing of dump passageway 58, main liquidpressure is restored to chamber 40 which overcomes the force of spring43 (see FIG. 4) to thereby move plunger 23 in a direction to reduce thelength of the reciprocative movement of piston 21. The more limitedtravel of piston 2I results, as previously described, in less oil beingdischarged through tapped outlets 30 and 31.

It is believed now readily apparent that the present invention providesa novel liquid metering device in which the rate of liquid dischargeautomatically varies in proportion to a predetermined r.p.m. of arotating mechanism. It is a liquid metering devices which can becombined with a liquid pump in a compact unitary housing. It is a liquidmetering device which is characterized by its simplicity of design,rugged construction, the logical and compact arrangement and assembly ofits components parts and units and the extreme facility with which itcan be adjusted and repaired.

Although two embodiments of the invention have been illustrated anddescribed in detail, it is to be expressly understood that the inventionis not limited thereto. Various changes can be made in the arrangementof parts without departing from the spirit and scope of the invention,as the same will not be understood by those skilled in the art.

What is claimed is:

I. In a liquid metering device having a double-acting pistoncylinderassembly for receiving pressurized liquid and discharging the samealternately from opposite ends of the cylinder of said piston-cylinderassembly upon reciprocative movement of the piston therein and includinga pistoncylinder mechanism having a cylinder adjacent the double actingpiston-cylinder assembly with the piston having a portion thereofextending into the cylinder of said double-acting piston-cylinderassembly to limit the extent of the stroke of the piston of saiddouble-acting piston-cylinder assembly, the improvement comprising:

a. passageway means for conducting pressurized fluid to saidpiston-cylinder mechanism to urge the piston of the piston-cylindermechanism in one direction relative to said double-actingpiston-cylinder assembly;

b. means for urging said piston-cylinder mechanism in an oppositedirection relative to said double-acting pistoncylinder assembly;

c. a dump passageway disposed to communicate said passageway means witha point of lower fluid pressure; and

d. valve means for simultaneously controlling pressurized fluid flowthrough said passageway means and said dump passageway in response tothe angular velocity of a source of rotary power so as to effectreciprocative movement of said piston of the piston-cylinder mechanismand change the length of the stroke of the piston of the double-actingpiston-cylinder assembly.

2. The apparatus of claim I, wherein said means for urging the piston ofthe piston-cylinder mechanism is a spring which biases the piston towarda position allowing the piston of the double-acting piston-cylindermechanism the maximum length of stroke.

3, The apparatus of claim I, wherein said valve means is a spool valveconstructed and arranged to reciprocate relative to said passagewaymeans and the dump passageway.

4. In a liquid metering device having a double-acting pistoncylinderassembly for receiving pressurized liquid and mechanism in an oppositedirection relative to said double-acting piston-cylinder assembly; and

a dump passageway disposed to communicate the discharging the samealternately from opposite ends of the cylinder of said piston-cylinderassembly upon reciprocative movement of the piston therein, theimprovement comprising: d.

a. piston-cylinder mechanism having a cylinder adjacent the cylinder ofsaid piston-cylinder mechanism with a point of double-actingpiston-cylinder assembly with the i ton 5 lower fluid pressure than saidsource of fluid pressure; having limit means extending into the cylinderof said and I double-acting piston-cylinder assembly to limit the extenta p l v e disposed In said passageway nean nd of the reciprocativemovement of the piston of the douump passageway for reciprocablemovement in response bl ri i tonylinder bl to the angular velocity of asource of rotary power for b passageway means for communicating thecylinder of Slmultaneousl) controlling flow 0r fluid 8 saidpiston-cylinder mechanism with a source of prespassageway means'and Pthemby effcct ITCCIPTOCPIWE surized fluid to force the piston of thepiston-cylinder movemm of said Plston or the plswn'cylmder mechanism inone direction relative to said double-acting "'f and Chang? length PStroke of the pistomcylindsr assembly; piston of the double-actingpiston-cylinder assembly. c. means for moving said piston of thepistonacylinder t UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,639,082 Dated February 1, 1972 Inventor(s) Howard RussellCorwin It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 1, line '50 after the word "supported insert the word --for--line 70, the word "resulting" should read --regulating-- Column 2 line72 the word "the" should read -and- Column 4, line 57, the word "as"should read --in-- Column 6, line 24, remove the "s" from the word--devicesline 35, the word "not" should read --now-- line 52 after theword "said" add --piston of the-.

Signed and sealed this 11 th day of Jul} 1972.

(SEAL) Attest:

EDWARD M.F'LEPCHER, JR. ROBERT GOlTSCI-IALK Attesting OfficerCommissionerof Patents FORM pomso (m'ssl USCOMM-DC 60376-P69 I k U,S. GOERNMENY PRINTING OFFICE: 19.9 O-3$fl-33l

1. In a liquid metering device having a double-acting pistoncylinderassembly for receiving pressurized liquid and discharging the samealternately from opposite ends of the cylinder of said piston-cylinderassembly upon reciprocative movement of the piston therein and includinga piston-cylinder mechanism having a cylinder adjacent the double-actingpistoncylinder assembly with the piston having a portion thereofextending into the cylinder of said double-acting piston-cylinderassembly to limit the extent of the stroke of the piston of saiddouble-acting piston-cylinder assembly, the improvement comprising: a.passageway means for conducting pressurized fluid to saidpiston-Cylinder mechanism to urge the piston of the pistoncylindermechanism in one direction relative to said doubleacting piston-cylinderassembly; b. means for urging said piston-cylinder mechanism in anopposite direction relative to said double-acting pistoncylinderassembly; c. a dump passageway disposed to communicate said passagewaymeans with a point of lower fluid pressure; and d. valve means forsimultaneously controlling pressurized fluid flow through saidpassageway means and said dump passageway in response to the angularvelocity of a source of rotary power so as to effect reciprocativemovement of said piston of the piston-cylinder mechanism and change thelength of the stroke of the piston of the double-acting piston-cylinderassembly.
 2. The apparatus of claim 1, wherein said means for urging thepiston of the piston-cylinder mechanism is a spring which biases thepiston toward a position allowing the piston of the double-actingpiston-cylinder mechanism the maximum length of stroke.
 3. The apparatusof claim 1, wherein said valve means is a spool valve constructed andarranged to reciprocate relative to said passageway means and the dumppassageway.
 4. In a liquid metering device having a double-actingpiston-cylinder assembly for receiving pressurized liquid anddischarging the same alternately from opposite ends of the cylinder ofsaid piston-cylinder assembly upon reciprocative movement of the pistontherein, the improvement comprising: a. piston-cylinder mechanism havinga cylinder adjacent the double-acting piston-cylinder assembly with thepiston having limit means extending into the cylinder of saiddouble-acting piston-cylinder assembly to limit the extent of thereciprocative movement of the piston of the double-actingpiston-cylinder assembly; b. passageway means for communicating thecylinder of said piston-cylinder mechanism with a source of pressurizedfluid to force the piston of the piston-cylinder mechanism in onedirection relative to said double-acting piston-cylinder assembly; c.means for moving said piston of the piston-cylinder mechanism in anopposite direction relative to said double-acting piston-cylinderassembly; and d. a dump passageway disposed to communicate the cylinderof said piston-cylinder mechanism with a point of lower fluid pressurethan said source of fluid pressure; and e. a spool valve disposed insaid passageway means and dump passageway for reciprocable movement inresponse to the angular velocity of a source of rotary power forsimultaneously controlling flow of fluid through the passageway meansand to thereby effect reciprocative movement of said piston of thepiston-cylinder mechanism and change the length of the stroke of thepiston of the double-acting piston-cylinder assembly.